Various adjustable-length shelves are known in the prior art. U.S. Pat. No. 1,876,494, which issued to Furo on 6 September, 1932, discloses an adjustable shelf consisting of two overlapping sections pivotally coupled together. The lateral edges of the Furo shelf sections are cut-away to provide spurs for penetrating adjacent support walls when the shelf is mounted.
U.S. Pat. No. 4,155,312, which issued to Thorkildson on 22 May, 1979, discloses a two piece shelf which is telescopically adjustable in length. The lateral ends of the Thorkildson shelf are flanged to facilitate fastening the shelf to wooden structural members, as by nails or screws.
U.S. Pat. No. 534,959, which issued to Foster on 6 August, 1895, discloses a rack for books which consists of two hingedly coupled sections. To install the Foster rack, the end portions of the two shelf sections are fitted into corresponding notches formed in the upright shelf supports. The shelf is then pressed downwardly toward a horizontal position until the two shelf sections are brought in line with one another.
All of the prior art shelves and racks referred to above exhibit shortcomings which are overcome by the applicant's invention. The primary shortcoming is the need to permanently modify or deface the shelf supporting surfaces, such as by forming notches in the support walls for receiving the shelf ends or by mounting brackets and the like on the support walls for receiving screws or other fasteners.
Further, none of the prior art shelving systems are specifically adapted for mounting in an enclosure having non-parallel sidewalls. For example, school and gym lockers are often not perfectly rectangular in cross-section and thus the end surfaces of conventional shelves will not uniformly contact the interior locker sidewalls. This limits the stability and load-supporting capacity of such shelves and effectively prevents them from being maintained in position by frictional forces alone.
Accordingly, the need has arisen for an adjustable-length portable shelf which may be removably mounted within an enclosure, such as a locker, at a desired height without defacing or modifying the locker sidewalls.